1. Field of the Invention
The present invention relates to an exposure device which handles a roll-film tape and which is equipped with a mechanism for feeding the tape from a supply unit to a winding unit through an exposure stage. Furthermore, the present invention pertains to an exposure process to be executed by said exposure device.
2. Description of the Related Art
In order to achieve their compact and lightweight bodies, small electrical devices, such as portable phones and mobile devices, contain electronic circuit boards made of highly precise, thin film-shaped tapes (thereinafter called “tapes”).
Tapes of this type have a thin, wide and very long shape. Specifically, tapes have a thickness of 0.06 mm to 0.1 mm, but some of them are 0.05 mm or less in thickness. In addition, they have a width of 100 mm to 250 mm and a length of 700 m or so. Tapes are usually treated with wound around a roll.
When electronic circuits are formed on such a roll-shaped tape, an exposure device feeds the tape to an exposure section once each block. During this process, some troubles are prone to occur, such as the tape are loosened or angled while being pulled out. In order to avoid those troubles, Japanese Unexamined Patent Application Publication H04-299332 discloses an exposure device that is able to feed a tape laterally while the tape is being handled firmly.
The above-described exposure device has sprockets, and handles the tape having perforation. The sprockets rotate while the teeth of the sprockets are inserted into the holes of perforation of the tape, so that the tape is fed to the exposure stage firmly. Also, this perforation is used to align the tape with a mask. However, all of the tapes are not provided with perforation. Accordingly, when a tape having no perforation is used, perforation needs to be formed on the tape before the exposure process. Furthermore, the perforation of the tape may be damaged when the teeth of the sprockets are inserted into the holes of the perforation. Such damaged perforation is prone to deteriorate the accuracy of the alignment process.
On the other hand, Japanese Unexamined Patent Application Publication H06-045406 discloses an exposure device that is equipped with a mechanism for forming alignment holes on a tape in order to align a mask with the tape precisely. In this exposure device, the tape on which the holes have been formed by this mechanism is positioned on the exposure stage, and is then aligned with the mask. Finally, the tape is subjected to the exposure process.
In the above exposure device, the alignment holes of the tape are formed near the exposure stage. Therefore, the mechanism for forming alignment holes is likely to spread dust. The dust may be adhered to the tape by means of static electricity, thereby leading to the deterioration of resolution of the exposed patterns.
Taking the above disadvantages into account, the present invention has been conceived. An object of the present invention is to provide an exposure device which has an ability to carry out an exposure process precisely without generating and spreading contaminants. An additional object of the present invention is to present an exposure process to be executed by said exposure device.